AV100: Installed Gotham 13.2 - Now no files play!

I have installed Gotham 13.2 onto our AV100 box and now cannot play any files at all through it. When I click on VidOnMe to access XBMC, I get to the main Gotham screen and can progress to view the sources (usb0 and usb1) but each of the sources now appears twice. The files I want to play are all listed but I just get a beep when I try to play them.I installed XBMC 14.2.1 to see if this would override Gotham but it hasn't. Gotham still appears when I click on VidOnMe instead of XBMC 14.2.1. I now have to access XBMC 14.2.1 through the file manager window and can then play our files but after a few minutes of normal play the sound becomes delayed and 'unsynced' with the video.How can I remove Gotham 13.2 from the box?I would really like to take the box back to what we had when we took delivery of it as it worked perfectly.

After posting the questions above i read through a few forums (sorry! i should have done that first, i know) and i have successfully reset my av100 box to factory settings. The problem now is that the usb device that holds all of our video files - and was connected when Gotham 13.2 was installed - is now not visible either in file manager or via xbmc. i can see other devices and their files ok if i connect them so the usb ports are working fine. Is there any way to allow this device to be seen again by xbmc?